1. Field of the Invention
The present invention relates to an inclination maintaining system for a discharge chute, and more particularly to such a system for use with the discharge chute of a ready-mix concrete truck which maintains the chute at a selected inclination as the inclination of the body varies due to movement of the truck over an uneven surface while discharging concrete.
2. Description of the Prior Art
Existing discharge chutes for ready-mix concrete trucks are elongated in the direction of flow therethrough and have one end pivotally mounted on the rearward end of the body of the truck for movement about an axis extending horizontally and transversely of the truck. Such a chute receives concrete in flowable form at its mounting end and discharges the concrete at its distal end. The chute is provided with a hydraulic ram which has opposite ends connected to the body of the truck and to the chute so that extension and contraction of the ram varies the inclination of the chute relative to the body. The ram is connected to a hydraulic system by which the ram selectively is extended and contracted to position the distal end of the chute at a desired elevation above a location at which concrete is to be discharged. Such existing hydraulic systems are manually activated so that the inclination of the chute relative to the body does not change in the absence of manipulation by an operator.
It is frequently necessary to discharge concrete onto a surface along an elongated path of traversal. To distribute the concrete along the path the truck is moved in a forward direction along the path. During such movement over a surface having elevational irregularities, the inclination of the body of the truck to the horizontal varies as the forward and rearward wheels of the truck individually encounter the irregularities. As a result, the inclination of the chute, which is extended rearwardly from the body, varies so that elevation of the distal end of the chute above the location where concrete is being discharged varies correspondingly. As the truck moves over the irregularities, the distal end of the chute often strikes the surface with resulting damage to concrete forms thereon and to the chute. Even if there is no damage, the concrete is distributed irregularly. On the other hand, when the elevation of the distal end becomes great enough, concrete is discharged at unwanted locations, splashed over the surroundings, or otherwise wasted.
The inclination of the chute can be controlled manually with the prior art type of hydraulic system to maintain the inclination of the chute approximately constant during dumping. However, it is necessary to provide an extra man to control the chute since the usual crew is fully occupied during discharge of concrete with driving the truck and distributing the concrete laterally of its path. When an extra man is provided, it is necessary for him to walk beside the truck as it moves during concrete discharge to observe and to adjust the inclination of the chute. This work is inconvenient and often dangerous. Such manual control is, in any event, difficult when the surface over which the truck moves is highly irregular and broken.
As a result of these difficulties, it has long been recognized that it would be highly desirable to provide a system which would automatically and accurately maintain a predetermined inclination of the discharge chute of a ready-mix concrete truck during movement of the truck while pouring concrete.